wag54g upgrade to wag54gx2(srx200)

Hi, I recently upgraded my wag54g to wag54gx2(srx200).
I have a wireless network and have a wet54g in the garage to provide wireless internet to two PC's.
The signal strenght between the wag54g and the wet54g has been ok, not great but ok. (40%)

I was hoping that the wag54gx2 would improve this, but instead the strength is worse (20%),

Why is this?, can I change some of the settings to make it work better?